When a display device displays an image, it needs to utilize a shift register (a gate driving circuit) to scan a pixel unit. The shift register comprises a plurality of shift register units, each of which is corresponding to pixel units of one row. The shift register units realize progressive scanning drive of the pixel units of the display device to display images.
However, with the increasing of the number of pixels, the number of rows to be scanned by the shift register within one frame time increases, which thus requires a smaller layout area of the shift register unit and simpler circuit structure. For example, there exists a known shift register unit, which mainly comprises a buffer module, a pull-up module, a pull-down module, a maintenance module, a charging module and a discharging module. In the known shift register unit, the buffer module is as an input module of the shift register unit, and is configured to input a voltage of an output terminal of a previous row to the shift register unit, the pull-up module is configured to pull up a level of the output terminal to a high level, the pull-down module is configured to pull down the level of the output terminal to a low level, the maintenance module is configured to maintain the level of the output terminal, the charging module is configured to ensure that transistors comprised in the pull-up module are capable of being turned on normally within operation time, and the discharging module is configured to discharge the charging module to turn off the pull-up module.
When the above shift register unit is in a discharging maintenance phase, due to existence of parasitic capacitance of transistors comprised in the pull-up module, a voltage of a pull-up node (i.e., a node connected to gates of the transistors comprised in the pull-up module) is pulled up, such that the transistors comprised in the pull-up module are turned on. In this way, a first clock signal terminal of the shift register unit would re-charge the output terminal. Therefore, in this shift register unit, noise exists in both the pull-up node and the output terminal.